An optical system includes, in order from an enlargement conjugate side to a reduction conjugate side, a front unit including a plurality of lenses, an aperture stop, and a rear unit including a plurality of lenses. A projection characteristic of the optical system representing a relationship between a half angle of view and an image height on an image plane satisfies a predetermined condition.

An optical system includes, in order from an enlargement conjugate side to a reduction conjugate side, a front unit including a plurality of lenses, an aperture stop, and a rear unit including a plurality of lenses. A projection characteristic of the optical system representing a relationship between a half angle of view and an image height on an image plane satisfies a predetermined condition.

An imaging lens that includes, sequentially from an imaging object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, and in which the first lens group includes a first lens (L1) having a positive refractive power; a second lens (L2) having a positive refractive power; a third lens (L3) having a negative refractive power; a fourth lens (L4) having a positive or a negative refractive power; a fifth lens (L5) having a positive or a negative refractive power; a sixth lens (L6) having a positive or a negative refractive power; and a seventh lens (L7) having a negative refractive power, and the second lens group includes, sequentially from the imaging object side, an eighth lens (L8) having a positive or a negative refractive power; and a ninth lens (L9) having a positive or a negative refractive power, and that causes an imaging device (201) to form an image of a subject is provided.

An imaging lens that includes, sequentially from an imaging object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, and in which the first lens group includes a first lens (L1) having a positive refractive power; a second lens (L2) having a positive refractive power; a third lens (L3) having a negative refractive power; a fourth lens (L4) having a positive or a negative refractive power; a fifth lens (L5) having a positive or a negative refractive power; a sixth lens (L6) having a positive or a negative refractive power; and a seventh lens (L7) having a negative refractive power, and the second lens group includes, sequentially from the imaging object side, an eighth lens (L8) having a positive or a negative refractive power; and a ninth lens (L9) having a positive or a negative refractive power, and that causes an imaging device (201) to form an image of a subject is provided.

An ocular optical system includes a first lens element and a second lens element from an eye-side to a display-side in order along an optical axis. The first lens element and the second lens element each include an eye-side surface and a display-side surface. The display-side surface of the second lens element has a concave portion in a vicinity of a periphery thereof. The ocular optical system satisfies 2.000≤G2D/T1 and ER/G12≤20.000, wherein G2D is a distance from the second lens element to the display screen along the optical axis, T1 is a thickness of the first lens element along the optical axis, ER is a distance from a pupil of the eye of the observer to the first lens element along the optical axis, and G12 is an air gap from the first lens element to the second lens element along the optical axis.

An ocular optical system includes a first lens element and a second lens element from an eye-side to a display-side in order along an optical axis. The first lens element and the second lens element each include an eye-side surface and a display-side surface. The display-side surface of the second lens element has a concave portion in a vicinity of a periphery thereof. The ocular optical system satisfies 2.000≤G2D/T1 and ER/G12≤20.000, wherein G2D is a distance from the second lens element to the display screen along the optical axis, T1 is a thickness of the first lens element along the optical axis, ER is a distance from a pupil of the eye of the observer to the first lens element along the optical axis, and G12 is an air gap from the first lens element to the second lens element along the optical axis.

A projection system includes a first optical system and a second optical system. The second optical system includes a first lens group disposed on an enlargement side of an intersection position where a chief ray of an off-axis beam having a maximum angle of view intersects with an optical axis of the projection system in the second optical system, a second lens group disposed on the reduction side of the intersection position and having negative power, and a third lens group disposed on the reduction side of the second lens group and having positive power. The second lens group includes a first lens having positive power, a second lens disposed on the reduction side of the first lens and having positive power, and a third lens disposed on the reduction side of the second lens and having negative power. The third lens group includes two lenses each having positive power.

A projection system includes a first optical system and a second optical system. The second optical system includes a first lens group disposed on an enlargement side of an intersection position where a chief ray of an off-axis beam having a maximum angle of view intersects with an optical axis of the projection system in the second optical system, a second lens group disposed on the reduction side of the intersection position and having negative power, and a third lens group disposed on the reduction side of the second lens group and having positive power. The second lens group includes a first lens having positive power, a second lens disposed on the reduction side of the first lens and having positive power, and a third lens disposed on the reduction side of the second lens and having negative power. The third lens group includes two lenses each having positive power.

Embodiments of the present application provide a lens system, a finger identification apparatus and a terminal device, including a first lens, a second lens and a third lens arranged sequentially from an object side to an image side, where the first lens is a S-shaped meniscus negative optical power lens, the second lens is a biconvex positive optical power lens and a focal length of the first lens and a focal length of the second lens follow a first relationship so that a field of view (FOV) is greater than a first threshold.

Embodiments of the present application provide a lens system, a finger identification apparatus and a terminal device, including a first lens, a second lens and a third lens arranged sequentially from an object side to an image side, where the first lens is a S-shaped meniscus negative optical power lens, the second lens is a biconvex positive optical power lens and a focal length of the first lens and a focal length of the second lens follow a first relationship so that a field of view (FOV) is greater than a first threshold.